CODEWITHSUNDEEP
iphoneiosautomatic-ref-counting
Dylan Reich
Dylan Reich

Reputation: 1430

ARC error when declaring delegate ivar

I am using ARC (no, this is not NDA). I am declaring my ivar in my interface with 

id itemDelegate;

I then declare the property:

@property (nonatomic, weak) id<mySecretDelegateYouAreNotSupposedToSeeOnSO> itemDelegate; (with weak instead of assign because of ARC)

In my implementation file I simply synthesize it: @synthesize itemDelegate;

However, I am getting the error: 

"Existing ivar 'ItemDelegate' for _weak property 'itemDelegate' must be _weak".

Anyone know what's wrong? Thanks for your help.

ARC - Automatic Reference Counting

Upvotes: 27

Views: 17877

Answers (3)

snibbe
snibbe

Reputation: 2738

There is an issue where, even if you update XCode (4.2+) from the Mac App Store, as Apple requires, it leaves the old version of XCode on your computer. So, if you had XCode pinned to your launchpad, and launch it, you'll get all these errors as noted below. You have to find the newer version of XCode, say by using the Spotlight feature, run it, and then as one of its first tasks, it removes the old version of XCode. Then you have no more errors reporting like this.

Upvotes: 1

Wolfgang Schreurs
Wolfgang Schreurs

Reputation: 11834

With ARC and iPhone Simulator 5.0 the following seems to work just fine (no warnings, etc...):

SomeObject.h

@class SomeObject;
@protocol SomeObjectDelegate <NSObject>
- (void)someObjectDidFinishDoingSomethingUseful:(SomeObject *)object;
@end


@interface SomeObject : NSObject {
   __unsafe_unretained id <SomeObjectDelegate> _delegate;
}
@property (nonatomic, assign) id <SomeObjectDelegate> delegate;
@end

SomeObject.m

#import "SomeObject.h"

@implementation SomeObject
@synthesize delegate = _delegate;
@end

Upvotes: 9

Wolfgang Schreurs
Wolfgang Schreurs

Reputation: 11834

Try something like the following (example from: http://vinceyuan.blogspot.com/2011/06/wwdc2011-session-323-introducing.html):

@interface SomeObject : NSObject {
   __weak id <SomeObjectDelegate> delegate;
}
@property (weak) id <SomeObjectDelegate> delegate;
@end

Please notice how the ivar is declared.

Upvotes: 46

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